The Clean Air Amendments of 1970 broadened the scope of public environmental concern on ambient air quality standards to deal with problems far beyond the health needs of humans and wildlife, adding such concerns as economic values, personal comfort, well being. It increased authority of regulatory control bodies and provides for citizen suits for prodding enforcement of the Act.
The discharge to atmosphere of smoke and odor emissions from small commercial establishments including fast food restaurants and other family-type restaurants which have meat-cooking grills, is considered objectionable by air pollution regulatory agencies. The impact from these sources on air pollution may be small for each individual source, but is considered large for the entire source category.
Most of the individual states have passed laws which have established state regulatory agencies with powers to set and enforce regulations relating to air quality. The standards which have been set by the states are varied. For example, the state air quality regulations consist of three major parts:
1. Maximum Grain Loading (GR/DSCF). PA0 2. visible Emissions. PA0 3. Odors.
Most states allow emissions up to 0.04 GR/DSCF; some not over 0.03 GR/DSCF.
Typically, visible emissions are permitted up to 40% opacity on existing sources, but may not exceed 20% opacity on new sources. The State of Maryland allows "no visible emissions".
Odor emission regulations have been adopted by thirty-seven state air quality bureaus. In general terms, a typical state odor emission regulation states that no person shall cause . . . odor emissions . . . beyond property line . . . unless . . . all gases are incinerated to (1200.degree. F.) (1600.degree. F.) for at least (0.5) (0.3) seconds. None of the state regulations are specific to the fast food or family-type restaurant. Similar to other small establishments, they are considered as a fixed source of air pollution regardless of their size.
On a county and/or local level, in absence of specific regulations, smoke and odor emission control is handled on a public nuisance basis.
The best available technology applied to these small sources has included that of incineration using afterburners which are too expensive in terms of energy usage and its costs, where available. Electrostatic precipitators have been found efficient in reducing smoke, but are not dependable due to the grease in the air stream which adds maintenance cost. In addition to the high initial costs of the units, they do not abate odors.
For instance, using an afterburner unit to eliminate odor and visible emissions from a 3500 CFM air stream (average exhaust from a family-type restaurant) requires 3,000,000 BTU/HR supplied to an oxidizing chamber at 1200.degree. F. Using natural gas at $0.15 per therm, the cost for each hour of operation of such an afterburner unit is $4.50. Using L.P.G., where and if available, at $0.35/gallon (North East Coastal Areas), the cost is $11.00 per hour of operation. The costs of maintaining the cleanliness of the collector plates to retain their efficiency when applied in a grease-laden air stream is estimated at $300.00 per month.
In order to determine how best to reduce or eliminate objectionable airborne emissions, the present inventor has conducted a series of tests, monitored by an Environmental Protection Agency representative from the Emission Measuring Branch, Research Triangle Park, N.C., of a typical, conventional fast food restaurant char-boiler, without emission-reduction equipment in order to provide a base line against which reductions can be measured and in order to permit a determination to be made of the make-up of the gases exhausted by such a facility. The conditions and particulars of the test and a tabulation of the stack analysis are incorporated in Emission Report dated Mar. 18, 1974, and Nov. 7, 1975, conducted by Commonwealth Laboratory, Inc., Richmond, Va., and are summarized herein.
Unlike emissions from heavy process manufacturing facilities which are steady and continuous for each hour of operation, the visible and odor emissions from small establishments including fast food or family-type restaurants are intermittent. They are characteristically heavy and are only difficult to operate in compliance with air quality regulations during the lunch and supper periods.
In the course of studying this development, the present inventor has become aware of the following prior art relating injection of an oxidizer of other fluid into a fluid stream for oxidizing or otherwise treating a portion of the contents thereof:
______________________________________ Patentee U.S. Pat. No. Date of Issue ______________________________________ Woodward 2,745,714 May 15, 1956 Urban 2,956,856 October 18, 1960 Barton et al. 3,054,653 September 18, 1962 Gonzalez 3,381,679 May 7, 1968 Wright 3,786,739 January 22, 1974 ______________________________________
The Woodward patent suggests the use of a shower of chlorine-containing water for deodorizing offensive organic odors in the gases generated in a fat-rendering process. Gonzalez relates to scrubbing of a gas stream from a cooking source and suggests the use of venturi for aspirating a treating liquid into the gas stream for mixed passage through the ductwork of a hood over the cooking area.
The U.S. Pat. to Newcomer, No. 3,762,394, issued Oct. 2, 1973 discloses an afterburner as an alternative to chemically oxidizing odiferous gases.
However, none of these references addresses the specific problem of small establishments, including fast food and family-type restaurant char-boiling grill exhaust streams, containing objectionable odor and visible emissions, and specifically, the reduction of the impact of these exhaust streams or air quality on an economical basis.